Apparatus for smoothing hot melt coatings



p 0, 1946. A. M. WICKWIRE, JR 2,407,335

APPARATUS FOR SMOOTHING HOT MELT COATINGS Original Filed Dec. 31, 1941 INVENTOR ART/f0? M MC/(W/Af, JR.

ATTORNEY leveling Patented Septa 1 e es STATES PATENT OFFICE I z manarcs roa sfi o 'i'nmo not: new I Arthur M. Wlckwire, In, Great terchemical assignor to In Harrington. Mum, Corporation. New

York, N. Y., a corporation of Ohio .Origiual application Deoember :1, 1941, Serial No. 425,211. Divided and this application myio. 1943. Serial No. 484,387

a cream. (ouresa) level film. I have also found that the reciprocaof my copending application Serial #425,2ll filed Dec. 31, 1941.

Due to the fact-that a rotogravure cylinder having an all-over screen pattern on the printing surface thereof provides a means of accurately regulating the amount of coating material applied, such cylinders are now being used rather extensively in the continuous application of coating materials to webs of paper and the like. When the coating composition applied is a thermoplastic or hot melt material, it is usually necessary to provide some means of smoothing and the gravure cylinder in order to produce a glossy and smooth surface. Various forms of apparatus have been suggested for this purpose and most of them involve the use of a heated bar or shoe having a smooth surface for contacting and heating the applied coating material so that it may be smoothed as the web passes thereover.

fully, they do not always function etilcien'tly over wide ranges of speed and with coating materials having comparatively high melting points.

I have discovered that smoothing of hot melt coating materials applied with a gravure cylinder is most effectively accomplished when the heated smoothing bar or other smoothing means is reciprocated back and forth as the coated web passes over it; and I have invented an improved apparatus for smoothing a wide variety of hot the small dots .of material applied by tion tends to dislodge any foreign matter that may be present'onthe coating or on the smoothing deviceand, therefore, eliminates thazjminute scratches caused by such matter. One form of smoothing device embodying the principles of my invention includes a plurality of substantially vertically arranged, closely spaced heated smoothing bars or scraper blades which preferably have narrow rounded faces for contactin the coated surface and are reciprocated back and forth as the web passes over them. when a plurality of blades are provided, it is desirable to have them arranged so that alternate blades move in opposite directions during their reciprocation. The effectiveness of theaction of the blades or bars may be increased by providing breaker bars or rollers adjacent the uncoated side of the paper and arranged between the blades so that the-angle and pressure of contact of the web with the blades may be suitably adjusted for different speeds and different coating materials.

The above and other features and objects of I my invention will become apparent upon consid- .eration of the following detailed description and the accompanying drawing, in which:

Fig. 1 is a somewhat diagrammatic elevational view, partly in section, showing a complete coat- 'While many of these are now being used suecessmelt coatings at considerably higher speeds than were heretofore obtainable.

In accordance with my invention, hot melt coatings are applied to one surface of'a moving web by means of a rotogravure cylinder which deposits the material in a multiplicity of regularly spaced uniform dots or quantities. The thus coated surface is smoothed into a glossy film of uniform thickness by passing the web angularly over a reciprocating heated smoothing device which acts to re-melt the material if it has solidified and spread and laterally sweep the small dots out sidewise and in all directions so as to fill all the spaces and produce a continuous ing apparatus in which my invention has been embodied;

Fig. 2 is a plan view of the smoothing apparatus showing the disposition of the blades and their manner of reciprocation;v and Fig. 3115 an enlarged fragmentary vertical sectional view showing the construction and manner of mounting the individual smoothing bars.

As shown in the drawing; a web W of paper or other material to be coated is fed.from a suitll. Coating-cylinder i0 is arranged to rotate in the'bath of the coating material which is con-- tained within a suitable heated fountain or housing ll. As the web W leaves the coating apparatus C, it has the coating material applied to or dots and is passed through a smoothing apparatus 8 constructed in accordance with the principles of my invention and adapted to smooth and level out the closely spaced uniform dots into a continuous film. The web may then be cooled in any convenient manner such as by means of an air blast A and cut into sheets or fed to any other. desired web treating or handling tippers-- tus.

Smoothing apparatus 8 comprises a plurality of substantially vertically arranged bars or blades. Ii, It, 2. and 22. I have shown four smoothing bars tional manner.

maintained in a proper heatedv condition in its passage through the smoothing apparatus. These breaker bars are connected, as by means of sup porting rods I52. to an adiustably mounted holding or supporting member 54 which is arranged to be moved upwardly and downwardly in any conven- As shown, the supporting mem- .ber 54 is supported on downwardly extending or blades in the present instance but it will be.

understood that depending upon the type of coatlug-material and the speed of movement of the web W, more or less blades may be used, as desired. Each of the blades, II, II, "and 22 is identical in construction and, as shown in Fig. .3.

screws l8 which are threaded in brackets E58 attached to a suitableside frame structure (not shown).

From the foregoing'description, it will be understood' that I have provided a method of and apparatus for smoothing hot melt coatings which is particularly advantageous in leveling out such.

coating material that has been applied to a moving web with a rotogravure cylinder, though ob viouslymy-invention is not restricted in its use consists of a thin. iiat metal blade or bar 24 hav mounted in a slotted rectangular holding member a ing an upper rounded web-contacting edge fl and zontally-disposed recess II provided in a heatin block 32 and opening into a substantially vertl-" cally disposed slot or opening 34 through which the blade extends.

The heating block is provided throughout the 928. Holder 28 is slidably received in a horispaces between the passages I4 with openings 38 for the insertion of any suitable heating means such as electric strip heaters; or, if desired, they may be connected with a heating system for circulating a heating fluid through them. In any event, the heating means provided should be suilicient to heat the block 82 so that the smooth- 36 temperature. Consequently, it is desirable to have I the bars placed as closely together as possible in 1 ing' bars maybecome heated to an elevated the heating block so that they may be properly heated and so that the web will not cool apprecia blv in passing from one to another. Should the blades themselves be constructed of heavy enough stock, it is desirable to mount heating means ll directly in the upper ends thereof which project, beyond the top surface of the heating block ll.

Referring tong 2, it will be noted that the smoothing bars I! and II. or at least the holders 2. thereof. project beyond one side of the heatingblock 32 and are connected to an actuating member 40. Similarly, the smoothing bars IO and I2,

or the holding members 28 thereof, project beyond the other side of the heated block 32 and are connected to an actuating member 42. Each of the actuatlngmembers N and 42 is operatively con nected to some suitable reciprocating mechanism which is adapted to cause all of the smoothing bars II, II, 2l and 22 to be reclprocated back and forth as the web W passes over them. For example, actuating member 40 may be plvotally con; nected at 44 to a link 48 which has its other end pivoted at the edge of a rotating disc 4! so that,

member 40 to be reciprocated back and forth a distance substantially equal to the diameter of the disc.

In order that the web ;w may pass over each of the smoothing bars or blades at an angle, I have provided a plurality of breaker bars or rollers ll which are arranged above the web to cause it to be passed angularly upwardly and then downwardly in traveling over each smoothing bar, and are preferably provided with vsome suitable in-- ternal heating means so that the web may be so as said disc rotates, it will cause the actuating to such application of the coating material. Due to the fact that each heated smoothing bar m -reciprocated as the coated web passes over it. the

individual regularly spaced dots of coating material are spread both longitudinally wlthlthe move- A ment of the web and laterally with a sweeping action produced by the reciprocation, and thus merged or integrated into a smooth film of uni= orm thickness, and the minute scratches caused y'the presence of foreign matter on the coating or on the smoothing bar are eliminated. The similarly acting smoothing bars or blades supplemen t each other in their effect on the coating and inthe production of a smooth and properly regus lated and leveled film.

' While I have described one preferred emimdi-v ment of the apparatus features of my invention, it will nevertheless be understood that various changes may be made in the construction and and means for reciprocating said bar's while the I coating material is in contact therewith.

2. Apparatus for smoothing thermoplastic coating material that has been applied to the suriace or-a sheet or web, comprising a plurality of spaced bars having upper smooth curved surfaces for contacting the coating material, means for heating each of said surfaces to an elevated temperature. a plurality of breaker rollers disposed in the spaces between said bars in a position below the curved surfaces of said bars, and means for re ciprocating said bars while the coating material is in contact therewith.

8. Apparatus for smoothing thermoplastic coating material that has been applied to the surface of a sheet or web, comprising a plurality of spaced bars having smooth curved surfaces for contactin: the coating material, means for heating each of said surfaces to an elevated temperature, and means for causing adjacent bars to be reciprocated in opposite directions while the coating material is in contact therewith,

' ARTHUR M. '1 Ja. 

